Buprenorphine is an opioid used to treat opioid addiction and control pain, such as moderate pain. Traditional methods for the synthesis of buprenorphine use thebaine or oripavine as the starting material. These known methods of buprenorphine synthesis typically result in a level of impurities that is higher than the level acceptable according to guidelines of the International Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (“ICH”). Examples of impurities that can be present at unacceptable levels in preparations of buprenorphine include (4R,4aS,6R,7R,7aR,12bS)-3-(but-3-en-1-yl)-6-((S)-2-hydroxy-3,3-dimethylbutan-2-yl)-7-methoxy-1,2,3,4,5,6,7,7a-octahydro-4a,7-ethano-4,12-methanobenzofuro[3,2-e]isoquinolin-9-ol and (4R,4aS,6R,7R,7aR,12bS)-3-(cyclopropylmethyl)-6-((S)-2-hydroxy-3,3-dimethylbutan-2-yl)-1,2,3,4,5,6,7,7a-octahydro-4a,7-ethano-4,12-methanobenzofuro[3,2-e]isoquinoline-7,9-diol. Some methods of purification, such as chromatography, e.g., as disclosed in U.S. Pat. No. 8,492,547, may provide buprenorphine with an acceptable level of impurities but have associated higher costs or are difficult to apply on a commercial scale. Accordingly, there is a need for alternative pathways for preparing buprenorphine containing acceptable levels of impurities.